M1078 WTEC II Transmission Service Manual

[Ambeihl]

After doing all of the steps to diagnose my transmission issue we have determined that it is a transmission solenoid. So I will be removing the bottom portion of the transmission. Do anyone have any experience with replacing a solenoid and where to buy them new?


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[Suprman]

How did you determine that a solenoid is bad? Onboard diagnostics will give you a high solenoid resistance fault with a wire harness issue. When you drop the pan you can check the catch screen for particles. Allison sells all the parts.

 

[Ambeihl]

I have removed the transmission controller since it was burnt up. I have not reinstalled the new one due to fear of it burning up. I then tested the harness for continuity and all looked good from it. Next I went wire by wire testing the ohm ratings from the harness to each solenoid and the E solenoid came back way out of spec. I crawled under there yesterday to remove the pan but it looks like I will have to remove the front drive shaft to get to it. I will be ordering a drive shaft puller to help.


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[lmtvjunky]

Here's a peek, I had a similar problem, found out it was a harness pin issue, changed out C5 solenoid, the solenoid body is very heavy, like 75 lbs

 

[Ambeihl]

Thank you for the pictures. Did you have to remove the driveshaft to get to the solenoid? Also which harness pin was faulty on your truck?


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[Suprman]

All the aftermarket allison shops say its usually wiring related issues not solenoid. I have seen damaged harnesses on these trucks.

 

[Ambeihl]

I checked that harness back and forth and i could not find anything wrong with it. If you have something else to check on the harness or a better pin out guide I'm all ears.


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[NDT]

Ohm out the solenoid at the transmission Deutch connector, the ohm value is different than at the controller.

 

[snowtrac nome]

look at the harness in the trans I have seen them come apart and also melt down in high heat areas

 

[Ambeihl]

Just downloaded the entire service manual for the transmission and will be going pin by pin on the transmission connector. Trying everything possible to make sure that it is a solenoid or something internal before taking all the steps to drop the transmission pan. That drive shaft does not look fun to pull. I am almost certain that it is a solenoid because the TCM was repaired in in 2012 and it went bad again shortly after and I see no signs of the transmission pan being dropped for repairs and inspection.


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[lmtvjunky]

Solenoid was fine, replaced it anyways, new filters, gasket, etc, found pin connector related to C5 solenoid at harness to controller was loose, female pin connector was spread causing loss of contact, problem solved, Allison trannies are **** near flawless, it's usually wiring!

 

[Ambeihl]

Here's a peek, I had a similar problem, found out it was a harness pin issue, changed out C5 solenoid, the solenoid body is very heavy, like 75 lbs

Im stuck trying to get the pan down. I removed the drive shaft that was in the way but not the yoke on the transfer case. Do you have to remove that too?


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